Conventional radio products use a surface acoustic wave (SAW) filter to filter a radio frequency (RF) signal. The surface acoustic wave filter is an electromechanical device that converts electrical signals to a mechanical wave using the piezoelectric effect of a piezoelectrical crystal or ceramic material. The mechanical wave is delayed as the mechanical wave propagates across the surface of the piezoelectrical crystal or ceramic material. When the delayed mechanical wave is converted back to an electrical signal, the converted electrical signal may be used as a direct analog implementation of a finite impulse response filter. However, surface acoustic wave filters may be limited to frequencies up to approximately three (3) gigahertz (GHz) and have a fixed center frequency and bandwidth. Accordingly, conventional radio products require one or more surface acoustic wave filters for each frequency band of the radio product.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.